Solder processing is known in the art and is exemplified in U.S. Pat. No. 5,244,143 to Ference, et al., entitled “Apparatus and Method for Injection Molding Solder and Applications Thereof” and U.S. Pat. No. 6,527,158 to Brouillette, et al., entitled “Method and Apparatus for Forming Solder Bumps.”
C4NP is a new solder technology in the IMS family of solder processing. C4NP is IMS applied to wafer bumping. C4NP uses a solder dispense head under which molds are scanned to fill cavities therein with solder. To date, the prevailing solder dispensing mechanism has been a slot filled with molten solder that is injected into the mold cavities, which are the substrate cavities, under pressure.
This solder dispense mechanism provides for solder filling of individual mold plates, but is not amenable to manufacturing. The reasons for this are as follows:
(1) Since there is always a large volume of solder in the slot in contact with the mold plate, this solder must be contained after the fill is complete or it will spill out. Complex mechanical fixtures called “parking blades” are used that the head travels onto, parks, and then travels off of onto the next mold plate, i.e., substrate, cavities to be filled. With the foregoing required operations, there are several points where solder can leak out of the head which is not desirable for manufacturing; and
(2) The currently prevailing head configuration employs O-rings that can easily be damaged during these operations, thus requiring rework steps which severely limits the fill cycles.
These O-rings also typically have high friction against the mold plates and frequently causes O-ring instabilities in their O-ring grooves. Accordingly, there is an unmet need for a system that eliminates the present solder slot design described herein above and also eliminates the need for using sensitive, high friction O-rings. Such improvements and changes in design are essential if C4NP is to become a successful manufacturing technology.